Not Applicable
Not Applicable
Not Applicable
1. Field of the Invention
The present invention relates to a novel apparatus and methods for the forming of a building material that may replace more expensive materials or materials that are more limited in supply. The preferred method begins with an extruder with an extrusion die that produces an extruded shell preferably of plastic that may have various profiles but each shell has an open gap preferably formed in its top working surface between spaced and parallel edges of the shell. The shell is then conducted into and through a calibrator where a vacuum is applied to the exterior of the shell to maintain the shape of the shell as it passes through the calibrator. The calibrator has an injection bore that in the preferred embodiment allows the inserting of an injector nozzle of a mixing head injector into and through the injection bore, through a gap in the extruded shell, and into a central shell cavity of the extruded shell as the shell passes through the calibrator. In the preferred embodiment, the mixing head injector mixes and injects a foam core through its injector nozzle and through the injection bore to fill the central shell cavity and the gap downstream from the injector nozzle as the shell passes by the injection bore. The core expands and cures as the shell and core continue through the remainder of the calibrator.
2. Description of Related Art
A number of extrusion devices exist that can aid a person in understanding the art of extrusion and foam filled extrusions. In U.S. Pat. No. 5,783,125 issued to Bastone is disclosed reinforced extrusion products and method of making same. In U.S. Pat. No. 5,393,536 issued to Brandt, a coextrusion apparatus is addressed. These prior devices use a different apparatus for the mixing and injection of a central core and introduce the central core through the extrusion die rather than downstream as done in the present invention.
In U.S. Pat. No. 6,083,601 issued to Prince, a foam wood extrusion product is disclosed that is formed by the extrusion first of a foam core that then receives a coextruded plastic cladding.
A principal objective of this invention is to provide a novel and improved mixing head injector and a method for mixing and injecting a foam core within an extruded shell preferably of plastic having a central shell cavity and having an open gap. The foam core injection takes place downstream from an extrusion die and preferably while the shell passes through a calibrator resulting in a foam filled shell as the shell exits the calibrator. The preferred mixing head injector of the invention is novel, compact, simple, low-maintenance, and reliable for mixing a binary system foam core such as polyurethane or other suitable synthetic binary foam known in the art. Gas injection is incorporated in the mixing head injector for homogenization of the foam core. Preferably the mixing head injector is mounted in an injection bore of a calibrator. The foam core is injected from the mixing head injector into a central shell cavity through a gap in the shell and thereafter the core cures as the shell and core continue through the remainder of the calibrator.
A suitable plastic for the extruded shell is ASA commercially available in pellet form from Hughes Processing Incorporated of Costa Mesa, Calif.
In an alternative embodiment, the mixing head injector is replaced by a second extruder. The second extruder having an extruder port extrudes a foam core comprising a selected mixture of synthetic, plastic foam known in the art containing at least one filler selected from a group of fillers including glass spheres, wood flour, fly ash, chopped strand materials, or similar inert materials through the extruder port. Suitable blowing agents for the selected plastic foam as known in the art would be used with the second extruder. The foam core would be extruded into the central shell cavity of the extruded shell as it passes by the extruder port. The extruder port of the second extruder would be mounted into and through the injection bore of the calibrator.
In alternative methods, the injection of a foam core by the mixing head injector or the second extruder within the central shell cavity of an extruded shell can occur after the shell exits the calibrator. In such alternative methods, the shell is conveyed into and through a suitable mounting fixture and the mixing head injector or the second extruder is mounted in the mounting fixture. Preferably the mounting fixture has a mounting fixture bore in which the injector nozzle of the mixing head injector or extruder port of the second extruder can be mounted and the foam core is injected through the mounting fixture bore and into the central shell cavity through the gap in the shell as the shell passes through the mounting fixture and thereafter the core cures as the shell and core continue through the remainder of the mounting fixture. The mounting fixture can be a second calibrator.
A further object of the invention is to provide a timesaving and economical method and apparatus for the production of a foam filled extruded building material.
Additional and various other objects and advantages attained by the invention will become more apparent as the specification is read and the accompanying figures are reviewed.